Access control method, access control system and computer readable storage medium

Abstract

The invention relates to the technical field of information security, in particular to an access control method, an access control system and a computer readable storage medium. An anonymous voucher is generated for each user by introducing a Groth signature technology, so that the traceability of the user identity is guaranteed while subsequent data access verification is facilitated; the interstellar file system IPFS is introduced to reduce the storage pressure of the block chain, and the computing power overhead is reduced by means of the characteristics of the interstellar file system, so that the method can better adapt to large-scale users and high-frequency access scenes, and aims to solve the problem of how to reduce the computing power overhead of the block chain while tracing the user identity.

Description

Technical Field

[0001] This application relates to the field of information security technology, and in particular, to an access control method, an access control system, and a computer-readable storage medium. Background Art

[0002] With the development of emerging technologies such as cloud computing and the Internet of Things, data sharing has become a key part of the information society. However, the security risks and privacy issues of the centralized data storage mode adopted in traditional data sharing technologies have gradually emerged. In the centralized data storage method, data is centrally stored on a cloud server. Although it reduces the storage pressure of traditional databases to a certain extent, its privacy protection mechanism is still weak. In addition, in the actual application of data sharing, the existence of the data silo phenomenon further restricts the circulation and utilization of data. Therefore, how to balance data sharing and the privacy protection of sensitive data has become the focus of common concern in the academic and industrial circles.

[0003] Currently, relevant technical solutions have adopted the ring signature technology in cryptography and combined it with blockchain technology to solve the above problems. The ring signature technology can verify the authenticity of transaction data without exposing the user's identity, and the blockchain technology provides technical guarantees for data sharing and secure storage through the characteristics of decentralization, anti-tampering, and traceability.

[0004] However, the inventor found during the conception and implementation of this application that although the ring signature scheme provides complete anonymity, it has obvious deficiencies in identity traceability and is easily exploited by malicious users to achieve uncontrollable behaviors such as untraceable malicious data theft. And the current blockchain technology has a defect of excessive computing power overhead due to the Proof of Work (POW) mechanism that requires a large amount of computing resources.

[0005] In view of this, this application proposes an access control method, aiming to protect the privacy of sensitive information in data sharing, achieve anonymous protection of identities, support flexible and fine-grained access control, provide the ability to trace data access records, and a mechanism for holding accountable for illegal access behaviors. Summary of the Invention

[0006] The main purpose of this application is to provide an access control method, aiming to solve the problem of how to trace user identities while reducing the computing power overhead of the blockchain.

[0007] To achieve the above object, an access control method provided by this application is applied to an access control system including a data user, a data owner, a blockchain, and an InterPlanetary File System. The method includes the following steps:

[0008] S10. When the data owner receives a fragment access request sent by a data user, the data owner determines whether the Groth signature and the user identity in the fragment access request are legal;

[0009] S20. If it is legal, the data owner calls the key fragment storage location from the blockchain, obtains the key fragment associated with the key fragment storage location from the InterPlanetary File System, and sends the key fragment to the data user;

[0010] S30. The data user uses the Lagrange interpolation method to reconstruct the key fragment into a symmetric key ciphertext, and submits a data decryption request including the symmetric key ciphertext and the user identity to the blockchain;

[0011] S40. When the blockchain verifies that the symmetric key ciphertext meets the preset access policy, the blockchain sends the key plaintext corresponding to the symmetric key ciphertext to the data user.

[0012] Optionally, before the S10, it further includes:

[0013] S50. When receiving a user registration instruction sent by a registration requester, perform registration according to the following steps:

[0014] S51. The registration requester generates a public-private key pair , ;

[0015] S52. The registration requester sends an identity binding request to the authorization center , and the authorization center checks whether the public key exists;

[0016] S53. If it exists, the authorization center sends a random number to the registration requester. The registration requester randomly selects , calculates , , , , obtains , and takes as the signature and returns it to the authorization center;

[0017] S54. The authorization center verifies using the following formula to verify whether it holds:

[0018]

[0019] S55. If it holds, the authorization center randomly selects , calculates , , , , , output the Groth signature and send it to the user:

[0020]

[0021] S56, the registration requester verifies the authenticity of the Groth signature through the following formula :

[0022]

[0023] In the formula, e represents the symbol of the mapping, , , and represent four bilinear pairs, indicating that four pairs of generators , , , are mapped to a multiplicative cyclic group through a bilinear mapping, , , and both represent performing a multiplication operation between two bilinear pairs, is the generator of the multiplicative cyclic group , is the generator of the multiplicative cyclic group , pk is the public key, is the initialized public key, , represent embedding the attribute value into the Groth signature, that is, completing the attribute value embedding through exponentiation of the generator and the attribute value ;

[0024] S57, after successful verification, the registration requester generates a user qualification certificate and sends it to the authorization center, so that the authorization center takes the registration requester with the user qualification certificate as the data user.

[0025] Before the above S40, the following steps are also included:

[0026] S60, in the data encryption stage, perform AES symmetric encryption on the registration data provided by the registration requester to generate a data ciphertext , and encrypt the encryption key of the AES symmetric encryption using an attribute-based encryption algorithm to obtain a key ciphertext ;

[0027] S70, the key ciphertext After randomly splitting to generate key fragments, together with the data ciphertext they are stored in the InterPlanetary File System, and the storage location of the key fragments is marked by a hash value to obtain a hash storage address. The hash storage address is stored on the blockchain, so as to call the hash storage address from the blockchain to obtain the storage location of the key fragments during access control, and obtain the key fragments associated with the storage location from the InterPlanetary File System.

[0028] Optionally, step S60 specifically includes:[[]]

[0029] S61, assuming that the registration data includes the user identity and user attributes , the authorization center randomly selects , calculates , , , , and sets the user attribute private key as , and after sorting, we get:[[]]

[0030]

[0031] The authorization center sends the attribute private key SK to the data user

[0032] S62, after the data owner identifies different data plaintexts M with Mid, uses the AES symmetric key to encrypt the data plaintext M to obtain the data ciphertext ;

[0033] S63, the data owner sets the access policy W and encrypts the AES symmetric key based on the access structure to obtain the key ciphertext .

[0034] Optionally, after step S40, it further includes:[[]]

[0035] S80, when the data owner publishes a data transaction, inputs the user public key , the timestamp of the current transaction and the hash address of the target data transaction in the InterPlanetary File System , creates a data transaction , and after verifying the legality of the data transaction , writes the data transaction into the blockchain.

[0036] Optionally, the data transaction includes a data storage transaction and a data access transaction, and the verification of the data transaction includes data storage transaction verification and data access transaction verification;

[0037] Among them, the data storage transaction verification S81 specifically includes:

[0038] S811, every time the data owner distributes a key fragment , a storage transaction will be created and published to the blockchain , where is the current transaction timestamp, is the key fragment and the storage address in IPFS;

[0039] S812, the data owner uses the private key to sign the transaction , and then generates the corresponding anonymous certificate ; ;

[0040] S813, any user on the blockchain is allowed to use the public key and the anonymous certificate to verify the transaction ; if the verification proves to be passed, the current transaction is allowed to be written into the blockchain; otherwise, the transaction is ignored;

[0041] The data access transaction verification S82 specifically includes:

[0042] S821, the data user randomly selects , calculates the corresponding access public key , and securely stores the access private key ;

[0043] S822, the data owner randomly selects , calculates the corresponding commitment value for the ciphertext data , and sets the ElGamal commitment value set ;

[0044] S823, the data owner creates a data access transaction , uses to sign , generates the corresponding anonymous certificate , and then publishes to the blockchain. ;

[0045] Optionally, after S40, it further includes:

[0046] S90, during the data access process of the data user, the blockchain periodically verifies the commitment of the access request in the transaction at preset intervals to ensure the legality of the access request.

[0047] Optionally, S90 specifically includes:

[0048] S91. At intervals of the preset period, the data user sends an access request for the ciphertext to the blockchain . ;

[0049] Wherein, represents an information tag, represents an anonymous certificate, represents a commitment value;

[0050] S92. The blockchain parses the elements in the commitment value in the access request and and , calculates to obtain , and sends to the data owner;

[0051] Wherein, is the access public key;

[0052] S93. After the data owner receives , it verifies whether the following formula holds:

[0053]

[0054] If it holds, it notifies the blockchain to store the hash value storage address of the ciphertext in the InterPlanetary File System and return it to the data user; otherwise, access is refused and the protocol ends;

[0055] Wherein, is the private key .

[0056] In addition, to achieve the above object, the present application further provides an access control system, including: a memory, a processor, and an access control program stored on the memory and executable on the processor. When the access control program is executed by the processor, the steps of the access control method described in any one of the above are implemented.

[0057] In addition, to achieve the above object, the present application further provides a computer-readable storage medium, on which an access control program is stored. When the access control program is executed by a processor, the steps of the access control method described in any one of the above are implemented.

[0058] The present application has at least the following beneficial effects:

[0059] 1. Introducing the Groth signature technology to generate anonymous credentials for each user facilitates subsequent data access verification and provides guarantee for the traceability of user identities;

[0060] ​2. Introduce the InterPlanetary File System (IPFS) to reduce the storage pressure of the blockchain and leverage the characteristics of IPFS itself to reduce the computing power overhead, so as to better adapt to large-scale users and high-frequency access scenarios;

[0061] 3. Hide the real identity information of users through blinding operations. In the blinding process, the user identity is mapped to the decryption key through encryption operations, making the user's identity information visible only to the authorization center and remaining anonymous to other participating parties. Combining with the Groth signature technology, while protecting user privacy, it provides guarantee for the traceability of user identity;

[0062] 4. Adopt the Ciphertext-Policy Attribute-Based Encryption (CP-ABE) technology to generate flexible access policies according to the user attribute set, achieving fine-grained control of data access permissions. Combining with threshold secret sharing, randomly fragment the decryption key and store it distributively, thus enhancing the security of data and keys;

[0063] 5. Record all data access and transaction operations through the blockchain, and utilize the immutable feature of the blockchain to achieve complete traceability of access behaviors;

[0064] 6. During the data access process, the blockchain verifies the commitment of the access request in the transaction at preset intervals to ensure the legality of the access request process. Brief Description of the Drawings

[0065] Figure 1 It is a schematic flowchart of the first embodiment of the access control method of this application;

[0066] Figure 2 It is a schematic diagram of the time consumption of secret distribution involved in the embodiment of this application;

[0067] Figure 3 It is a schematic diagram of the time consumption of secret reconstruction involved in the embodiment of this application;

[0068] Figure 4 It is a schematic architecture diagram of the hardware operating environment of the access control system involved in the embodiment of this application.

[0069] The realization, functional features and advantages of the purpose of this application will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0070] To better understand the above technical solution, the exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0071] First Embodiment

[0072] In this embodiment, the execution subject is an access control system, and the access control system includes a data user, a data owner, a blockchain, and an InterPlanetary File System.

[0073] A data user (Date User, DU) refers to a user or entity that needs to access and use data; its function is to send an access request to the data owner or system, requesting to obtain specific data resources or perform specific operations, and after obtaining authorization, use the data according to the specified permissions and methods.

[0074] A data owner (Date Owner, DO) refers to a user or entity that owns data resources and has ownership and control over the data; its function is to be responsible for defining the access control policy of the data, that is, determining which users or entities can access the data, in what way to access, and the access permission level.

[0075] The blockchain records and verifies data in a decentralized manner, consists of a series of blocks, and each block contains transaction information within a certain period of time and is encrypted and linked through cryptographic technology.

[0076] The InterPlanetary File System (IPFS) is a peer-to-peer distributed file system that realizes distributed storage, privacy protection, and rapid location of files by splitting files into small pieces and giving users a unique hash value.

[0077] It should be noted that the complete anonymous access control privacy protection scheme includes six parts: system initialization, user registration, attribute encryption, distributed storage, transaction publication, and access control. In this embodiment, the access control in the data interaction process is taken as the core content for description.

[0078] Referring to Figure 1 , the access control method includes the following steps:

[0079] S10, when receiving a fragment access request sent by a data user to a data owner, the data owner determines whether the Groth signature and user identity in the fragment access request are legal;

[0080] In this embodiment, when a data user who is a legally registered user sends a fragmented access request, the fragmented access request should include a legal Groth signature and user identity information.

[0081] Exemplarily, let the fragmented access request expression be:

[0082]

[0083] The data owner DO parses and . Use the following formula to verify whether the equation holds:

[0084]

[0085] Where, in the formula, e is the symbolic representation of the mapping, , , and represent four bilinear pairs, indicating that the four pairs of generators , , , are mapped to a multiplicative cyclic group through bilinear mapping, , , and all represent performing a multiplication operation between two bilinear pairs, is the generator of the multiplicative cyclic group , is the generator of the multiplicative cyclic group , pk is the public key, is the initialized public key, , represent embedding the attribute value into the Groth signature, that is, completing the embedding of the attribute value through exponentiation of the generator and the attribute value ;

[0086] If it holds, determine that the fragmented access request is legal.

[0087] It should be noted that the Groth signature technology can provide efficient identity anonymization protection and at the same time support the traceability function of the user identity, thus avoiding uncontrollable behaviors such as malicious data theft that cannot be traced after being impersonated by a malicious user as a legitimate user identity. Therefore, in this embodiment, the Groth signature technology is introduced to generate anonymous credentials for each user, which are used for subsequent data access verification and at the same time provide guarantee for the traceability of the user identity.

[0088] S20, if it is legal, the data owner calls the storage location of the key fragment from the blockchain, obtains the key fragment associated with the storage location of the key fragment from the InterPlanetary File System (IPFS), and sends the key fragment to the data user;

[0089] In this embodiment, if it is judged to be legal, the data owner calls the storage location of the key fragment from the blockchain, obtains the key fragment associated with the storage location of the key fragment from the InterPlanetary File System (IPFS), and sends the key fragment to the data user.

[0090] The key fragment and its storage location are stored in the InterPlanetary File System (IPFS) and the blockchain respectively by the system after the data user completes registration. Specifically, in order to improve the security and anti-attack ability of the data, the key fragment is randomly divided by the threshold secret sharing algorithm, and the divided key fragments are stored in the InterPlanetary File System (IPFS). The storage location of each key fragment is marked by calculating the hash value, obtaining the hash storage location containing the hash value and the storage location, and storing the hash storage location on the blockchain.

[0091] It should be noted that in this embodiment, the purpose of introducing the InterPlanetary File System (IPFS) is, on the one hand, to reduce the storage pressure of the blockchain, and on the other hand, to shorten the time overhead of signature generation, transaction verification and access control, and better adapt to the scenarios of a large number of users and high-frequency access.

[0092] S30, the data user uses the Lagrange interpolation method to reconstruct the key fragment into a symmetric key ciphertext, and submits a data decryption request including the symmetric key ciphertext and the user identity to the blockchain;

[0093] S40, when the blockchain verifies that the symmetric key ciphertext meets the preset access policy, the blockchain sends the key plaintext corresponding to the symmetric key ciphertext to the data user.

[0094] In this embodiment, the data user uses the Lagrange interpolation method to reconstruct the key fragment into a symmetric key ciphertext.

[0095] Exemplarily, the symmetric key ciphertext has the following expression:

[0096]

[0097] In the formula, represents the sub-key share, that is, it is calculated by the n - 1 order polynomial , where , t represents the threshold of the secret sharing, and represent two unequal and non-zero random positive integers, and for any All have , Indicates a modulo operation on prime numbers .

[0098] Then, the data user submits a data decryption request containing the symmetric key ciphertext and the user identity . Only when the blockchain verifies that the attribute set of the data user satisfies the access policy W can the key plaintext be decrypted. Otherwise, the request is ignored and a decryption failure message is output.

[0099] In the technical solution provided in this embodiment, on the one hand, the Groth signature technology is introduced to generate anonymous credentials for each user, facilitating subsequent data access verification and providing guarantee for the traceability of user identity; on the other hand, the InterPlanetary File System IPFS is introduced to reduce the storage pressure of the blockchain, and with the help of the characteristics of the InterPlanetary File System itself, the computing power overhead is reduced, so as to better adapt to the scenarios of large-scale users and high-frequency access.

[0100] Second Embodiment

[0101] Based on the first embodiment, in this embodiment, for the user registration link before access control, the system proceeds according to the following steps:

[0102] S50, when receiving the user registration instruction sent by the registration requester, register according to the following steps:

[0103] S51, the registration requester generates a public-private key pair , ;

[0104] S52, the registration requester sends an identity binding request to the authorization center , and the authorization center checks whether the public key exists;

[0105] S53, if it exists, the authorization center sends a random number to the registration requester, and the registration requester randomly selects , calculates , , , , and obtains , and takes as the signature and returns it to the authorization center;

[0106] S54, the authorization center verifies whether the following formula holds:

[0107] ​

[0108] S55, if it holds, the authorization center randomly selects , calculates , , , , , outputs the Groth signature and sends it to the user:

[0109]

[0110] S56, the registration requester verifies the authenticity of the Groth signature through the following formula :

[0111]

[0112] In the formula, e represents the symbol of the mapping, , , and represent four bilinear pairs, indicating that four pairs of generators , , , are mapped to a multiplicative cyclic group through a bilinear mapping, , , and both represent performing a multiplication operation between two bilinear pairs, is the generator of the multiplicative cyclic group , is the generator of the multiplicative cyclic group , pk is the public key, is the initialized public key, , represent embedding the attribute value into the Groth signature, that is, completing the attribute value embedding through the exponentiation of the generator and the attribute value ;

[0114] S57, after successful verification, the registration requester generates the user qualification certificate and sends it to the authorization center, so that the authorization center takes the registration requester with the user qualification certificate as the data user.

[0115] In the technical solution provided in this embodiment, when a user registers in the system, first, the identity authentication is completed through a trusted authorization center. While generating the public-private key pair, the authorization center hides the user's real identity information through a blinding operation. During the blinding process, the user's identity is mapped to the decryption key through an encryption operation, making the user's identity information visible only to the authorization center and remaining anonymous to other participating parties. In addition, combined with the Groth signature technology, this design not only protects user privacy but also provides guarantees for the traceability of user identities.

[0116] Third Embodiment

[0117] Based on any of the above embodiments, in this embodiment, in order to improve the security and anti-attack ability of data, during the data encryption phase, after the data owner (DO) preprocesses the data to be shared, a symmetric encryption algorithm (such as AES) is used to encrypt the data to generate ciphertext data. At the same time, CP-ABE (Ciphertext-Policy Attribute-Based Encryption, an attribute-based encryption technology) is used to further encrypt the encryption key, and key fragments are generated in combination with the access policy. The key fragments are randomly divided through the threshold secret sharing algorithm, and the divided key fragments are stored in the IPFS network. The storage location of each key fragment is marked by calculating the hash value, and the hash value and the storage location of the data ciphertext are recorded in the blockchain together.

[0118] The specific steps are as follows:

[0119] S60, in the data encryption phase, perform AES symmetric encryption on the registration data provided by the registration requester to generate data ciphertext , and use the attribute-based encryption algorithm to encrypt the encryption key of the AES symmetric encryption to obtain the key ciphertext ;

[0120] S70, after randomly dividing the key ciphertext to generate key fragments, store them together with the data ciphertext in the InterPlanetary File System, and mark the storage location of the key fragments with the hash value to obtain the hash storage address. Store the hash storage address on the blockchain to call the hash storage address from the blockchain to obtain the storage location of the key fragments during access control, and obtain the key fragments associated with the storage location from the InterPlanetary File System.

[0121] Furthermore, the step S60 specifically includes:

[0122] S61, assume that the registration data includes the user identity and user attributes , and the authorization center randomly selects , calculate , , , , let the user attribute private key be , and after sorting, we get:

[0123]

[0124] The authorization center sends the attribute private key SK to the data user

[0125] S62. After the data owner identifies different data plaintexts M with Mid, the data owner uses the AES symmetric key to encrypt the data plaintext M to obtain the data ciphertext ;

[0126] S63. The data owner sets the access policy W and encrypts the AES symmetric key based on the access structure to obtain the key ciphertext .

[0127] In the technical solution provided in this embodiment, the ciphertext-policy attribute-based encryption (CP-ABE) technology is adopted to generate a flexible access policy according to the user attribute set, realizing fine-grained control of data access permissions. Combining threshold secret sharing, the decryption key is randomly sharded and stored distributively, thereby enhancing the security of data and keys.

[0128] Fourth Embodiment

[0129] Based on any of the above embodiments, in this embodiment, after the access control is completed, when the data owner publishes a data transaction, all data access and transaction operations are recorded through the blockchain, and the immutable feature of the blockchain is used to realize the complete traceability of access behaviors.

[0130] Specifically, after the step S40, it further includes:

[0131] S80. When the data owner publishes a data transaction, the user public key , the timestamp of the current transaction and the hash address of the target data transaction in the InterPlanetary File System are input to create a data transaction , and after verifying the legality of the data transaction , the data transaction is written into the blockchain.

[0132] Further and optionally, the data transaction includes a data storage transaction and a data access transaction, and the verification of the data transaction includes data storage transaction verification and data access transaction verification;

[0133] Among them, the data storage transaction verification S81 specifically includes:

[0134] S811, every time the data owner distributes a key fragment , a storage transaction will be created and published to the blockchain , where is the current transaction timestamp, is the key fragment and the storage address in IPFS;

[0135] S812, the data owner uses the private key to sign the transaction , and then generates a corresponding anonymous certificate ; ;

[0136] S813, any user on the blockchain is allowed to use the public key and the anonymous certificate to verify the transaction ; if the verification proves to be passed, the current transaction is allowed to be written into the blockchain; otherwise, the transaction is ignored;

[0137] The data access transaction verification S82 specifically includes:

[0138] S821, the data user randomly selects , calculates the corresponding access public key , and securely stores the access private key ;

[0139] S822, the data owner randomly selects , calculates the corresponding commitment value for the ciphertext data , and sets the ElGamal commitment value set ;

[0140] S823, the data owner creates a data access transaction , uses to sign , generates a corresponding anonymous certificate , and then publishes to the blockchain.

[0141] Fifth Embodiment

[0142] Based on any of the above embodiments, in this embodiment, after access control is completed, during the process of the DU accessing the DO, the blockchain verifies the commitment of the access request in the transaction at a preset interval to ensure the legality during the access request process. ​

[0143] Specifically, the commitment verification S90 specifically includes:

[0144] S91, at intervals of the preset period, the data user sends an access request for the ciphertext to the blockchain ;

[0145] In the formula, represents the information tag, represents the anonymous certificate, represents the commitment value;

[0146] S92, the blockchain parses the elements in the commitment value in the access request and calculates to obtain and sends to the data owner;

[0147] In the formula, is the access public key

[0148] S93, after the data owner receives , it verifies whether the following formula holds:

[0149]

[0150] If it holds, it notifies the blockchain to store the hash value storage address of the ciphertext in the InterPlanetary File System and return it to the data user; otherwise, access is refused and the protocol ends;

[0151] In the formula, is the private key .

[0152] Sixth Embodiment

[0153] Based on any of the above embodiments, this embodiment illustrates the access control system proposed in terms of data processing efficiency:

[0154] In this embodiment, the time consumption of running the single initialization, key generation, encryption and decryption, signature, and transaction verification algorithms of the proposed solution is shown in Table 1 below:

[0155] Table 1. Time Overhead of Main Algorithms (ms)

[0156] In the key generation phase, since this scheme encrypts the AES key fragments based on CP-ABE, in addition to generating the public and private keys required for signature and signature verification, it is also necessary to generate the corresponding user attribute private keys, thus incurring additional computational overhead. However, this scheme not only ensures the security of the key fragments, but also realizes fine-grained and flexible access control, and shows relatively prominent performance advantages in aspects such as encryption, decryption, and transaction verification.

[0157] In addition, this application also analyzes the time overhead of DU, DO, and establishing ElGamal commitment values when verifying a single transaction. The experimental results are shown in Table 2 below:

[0158] Table 2. Time overhead for commitment establishment (ms)

[0159] In addition, for the cases of security |p| = 256 bits and |p| = 512 bits, the number of users is gradually increased, the time overhead of secret distribution and secret reconstruction is tested, and the variation of the key distributed management time with the number of users under different security bit lengths is compared. The time consumption of secret distribution is as Figure 2 shown, and the time consumption of secret reconstruction is as Figure 3 shown.

[0160] It is easy to know that when the number of users is 50, in the case of |p| = 256 bits, the key distribution management time is about 17 ms; while in the case of |p| = 512 bits, it is about 48 ms, which is about 2.8 times that of the former. It can be seen that when the security bit length is increased, the time overhead of the key distributed management of the proposed scheme is acceptable when the number of users is large.

[0161] As an implementation scheme, Figure 4 is the architecture schematic diagram of the hardware operating environment of the access control system involved in the embodiment of this application.

[0162] As Figure 4As shown in the figure, the access control system may include: a processor 1001, such as a CPU, a memory 1005, a user interface 1003, a network interface 1004, and a communication bus 1002. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display) and an input unit such as a keyboard (Keyboard). The user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may optionally also be a storage device independent of the aforementioned processor 1001.

[0163] Those skilled in the art can understand that Figure 1 the access control system architecture shown in the figure does not constitute a limitation on the access control system, and may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0164] As Figure 4 shown, the memory 1005, as a storage medium, may include an operating system, a network communication module, a user interface module, and an access control program. Among them, the operating system is a program that manages and controls the hardware and software resources of the access control system, and runs the access control program and other software or programs.

[0165] In Figure 4 the access control system shown in the figure, the user interface 1003 is mainly used to connect to the terminal and perform data communication with the terminal; the network interface 1004 is mainly used to connect to the background server and perform data communication with the background server; the processor 1001 may be used to call the access control program stored in the memory 1005.

[0166] In this embodiment, the access control system includes: a memory 1005, a processor 1001, and an access control program stored on the memory and executable on the processor, where:

[0167] When the processor 1001 calls the access control program stored in the memory 1005, it performs the following operations:

[0168] S10, when receiving a fragmented access request sent by a data user to a data owner, the data owner determines whether the Groth signature and the user identity in the fragmented access request are legal;

[0169] S20. If it is legal, the data owner calls the storage location of the key fragment from the blockchain, obtains the key fragment associated with the storage location of the key fragment from the InterPlanetary File System, and sends the key fragment to the data user;

[0170] S30. The data user uses the Lagrange interpolation method to reconstruct the key fragment into a symmetric key ciphertext, and submits a data decryption request including the symmetric key ciphertext and the user identity to the blockchain;

[0171] S40. When the blockchain verifies that the symmetric key ciphertext meets the preset access policy, the blockchain sends the key plaintext corresponding to the symmetric key ciphertext to the data user.

[0172] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0173] S50. When receiving a user registration instruction sent by a registration requester, register according to the following steps:

[0174] S51. The registration requester generates a public-private key pair , ;

[0175] S52. The registration requester sends an identity binding request to the authorization center , and the authorization center checks the public key to see if it exists;

[0176] S53. If it exists, the authorization center sends a random number to the registration requester , and the registration requester randomly selects , calculates , , , , and obtains , and takes as the signature and returns it to the authorization center;

[0177] S54. The authorization center verifies using the following formula to verify to see if it holds:

[0178]

[0179] S55. If it holds, the authorization center randomly selects , calculates , , , , , outputs the Groth signature and sends it to the user:

[0180]

[0181] S56. The registration requester verifies the authenticity of the Groth signature through the following formula: :

[0182]

[0183] In the formula, , , and represent four bilinear pairs. Taking as an example, the generator is bilinearly mapped into a multiplicative cyclic group. , , and all represent multiplying two bilinear pairs. is the generator of the multiplicative cyclic group , is the generator of the multiplicative cyclic group . pk is the public key, is the initialized public key, , represent embedding the attribute value into the Groth signature. e is the symbol representation of the mapping;

[0184] S57. After successful verification, the registration requester generates a user qualification certificate and sends it to the authorization center, so that the authorization center takes the registration requester with the user qualification certificate as the data user.

[0185] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0186] S60. In the data encryption stage, the registration data provided by the registration requester is encrypted symmetrically by AES to generate a data ciphertext , and the encryption key for the AES symmetric encryption is encrypted using the attribute-based encryption algorithm to obtain a key ciphertext ;

[0187] S70. After randomly splitting the key ciphertext into key fragments, together with the data ciphertext They are stored in the InterPlanetary File System together, and the storage location of the key fragment is marked with a hash value to obtain a hash storage address. The hash storage address is stored on the blockchain so that the hash storage address can be called from the blockchain to obtain the storage location of the key fragment during access control, and the key fragment associated with the storage location can be obtained from the InterPlanetary File System.

[0188] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0189] S61. Assume that the registration data includes the user identity and user attributes , and the authorization center randomly selects , calculates , , , , and sets the user attribute private key as . After sorting, we get:

[0190]

[0191] The authorization center sends the attribute private key SK to the data user

[0192] S62. After the data owner identifies different data plaintexts M with Mid, the data plaintext M is encrypted using the AES symmetric key to obtain the data ciphertext ;

[0193] S63. The data owner sets the access policy W and encrypts the AES symmetric key based on the access structure to obtain the key ciphertext .

[0194] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0195] S80. When the data owner publishes a data transaction, the user public key , the timestamp of the current transaction and the hash address of the target data transaction in the InterPlanetary File System are input to create a data transaction . After verifying the legality of the data transaction , the data transaction is written into the blockchain.

[0196] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0197] S811. Each time the data owner distributes a key fragment , a storage transaction will be created and published to the blockchain , where is the current transaction timestamp, is the storage address of the key fragment in IPFS;

[0198] S812. The data owner uses the private key to sign the transaction , and then generates the corresponding anonymous certificate ;

[0199] S813. Any user on the blockchain is allowed to use the public key and the anonymous certificate to verify the transaction ; if the verification proves to be successful, the current transaction is allowed to be written to the blockchain; otherwise, the transaction is ignored;

[0200] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0201] S821. The data user randomly selects , calculates the corresponding access public key , and securely stores the access private key ;

[0202] S822. The data owner randomly selects , calculates the corresponding commitment value for the ciphertext data , and sets the ElGamal commitment value set ;

[0203] S823. The data owner creates a data access transaction , uses to sign , generates the corresponding anonymous certificate , and then publishes to the blockchain.

[0204] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0205] S90. During the data access process of the data user, the blockchain periodically verifies the commitments in the transaction at preset intervals to ensure the legitimacy of the access request.

[0206] When the processor 1001 calls the access control program stored in the memory 1005, the following operations are performed:

[0207] S91, at intervals of the preset period, the data user sends an access request for the ciphertext to the blockchain ;

[0208] Wherein, represents an information tag, represents an anonymous certificate, represents a commitment value;

[0209] S92, the blockchain parses the elements in the commitment value in the access request and , calculates to obtain , and sends to the data owner;

[0210] Wherein, is the access public key;

[0211] S93, after the data owner receives , verifies whether the following formula holds:

[0212]

[0213] If it holds, notifies the blockchain to store the hash value storage address of the ciphertext in the InterPlanetary File System and returns it to the data user; otherwise, rejects the access and the protocol ends;

[0214] Wherein, is the private key .

[0215] In addition, those of ordinary skill in the art can understand that all or part of the processes in the methods of implementing the above embodiments can be completed by instructing relevant hardware through a computer program. This computer program includes program instructions, and the computer program can be stored in a storage medium, and this storage medium is a computer-readable storage medium. The program instructions are executed by at least one processor in the access control system to implement the process steps of the above method embodiments.

[0216] Therefore, the present application also provides a computer-readable storage medium, and the computer-readable storage medium stores an access control program. When the access control program is executed by a processor, it implements each step of the access control method as described in the above embodiments.

[0217] Among them, the computer-readable storage medium may be a U disk, a mobile hard disk, a read-only memory (ROM), a magnetic disk, an optical disk, or other various computer-readable storage media that can store program codes.

[0218] It should be noted that since the storage medium provided in the embodiments of the present application is the storage medium used to implement the methods in the embodiments of the present application, those skilled in the art can understand the specific structure and variations of the storage medium based on the methods introduced in the embodiments of the present application. Therefore, it will not be elaborated here. Any storage medium used in the methods of the embodiments of the present application falls within the scope of protection of the present application.

[0219] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program codes.

[0220] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0221] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0222] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide means for implementing the functions in the processFigure 1 One process or multiple processes and / or blocks Figure 1 Steps of the functions specified in one block or multiple blocks

[0223] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0224] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these changes and variations.

Claims

1. An access control method, characterized in that: Applied to an access control system including a data user, a data owner, a blockchain and an interplanetary file system, the method comprises the following steps: S10, upon receiving a fragment access request sent by a data user to a data owner, the data owner determines whether the Groth signature and user identity in the fragment access request are legal; S20, if legal, the data owner calls the key fragment storage location from the blockchain, obtains the key fragment associated with the key fragment storage location from the InterPlanetary File System, and sends the key fragment to the data user; S30, the data user reconstructs the key fragment into a symmetric key ciphertext using the Lagrange interpolation method, and submits a data decryption request including the symmetric key ciphertext and the user identity to the blockchain; S40, when the blockchain verifies that the symmetric key ciphertext satisfies the preset access policy, the blockchain sends the key plaintext corresponding to the symmetric key ciphertext to the data user.

2. The method according to claim 1, characterized in that Before S10, it also includes: S50, upon receiving the user registration instruction sent by the registration requester, register according to the following steps: S51, the registration requester generates a public-private key pair , ; S52, the registration requester sends an identity binding request to the authorization center , the authorization center checks the public key exists; S53, if it exists, the authorization center sends a random number to the registration requester , the registration requester randomly selects ,calculate , , , ,get ,Will Returned to the Authorization Center as a signature; S54, the authorization center verifies using the following verification method Is it established: ； S55, if established, the authorization center randomly selects ,calculate , , , , , output Groth signature And send to the user: ； S56, the registration requester verifies the Groth signature by the following formula Authenticity: ； Where e is the symbolic representation of the mapping, , , and Represents four double pairs, indicating that the element will be generated , , , Through a bilinear mapping to a multiplicative cyclic group, , , and Both represent multiplication between two pairs of lines. is the multiplicative cyclic group The generator of is the multiplicative cyclic group The generator of , pk is the public key, To initialize the public key, , Indicates that the attribute value Embedded in the Groth signature, that is, through the generator With attribute value Perform exponential operation to complete attribute value embedding; S57, after successful verification, the registration requester generates a user qualification certificate Then it is sent to the authorization center so that the authorization center will regard the registration requester with the user qualification certificate as the data user.

3. The method according to claim 1 or 2, characterized in that Before S40, the following steps are also included: S60, in the data encryption stage, the registration data provided by the registration requester is symmetric encrypted by AES to generate data ciphertext , and encrypt the encryption key of the AES symmetric encryption using an attribute-based encryption algorithm to obtain a key ciphertext ; S70, the key ciphertext After randomly splitting and generating key fragments, the same data ciphertext The key fragments are stored together in the InterPlanetary File System, and the storage location of the key fragment is marked with a hash value to obtain a hash storage address, and the hash storage address is stored on the blockchain, so that the hash storage address can be called from the blockchain to obtain the storage location of the key fragment during access control, and the key fragment associated with the storage location can be obtained from the InterPlanetary File System.

4. The method according to claim 3, characterized in that The step S60 specifically includes: S61, set the registration data to include user identity and user attributes , the authorization center randomly selects ,calculate , , , , let the user attribute private key be , sorted out: ； The authorization center sends the attribute private key SK to the data user S62, the data owner uses Mid to identify different data plaintext M, and then uses the AES symmetric key Encrypt the data plaintext M to get the data ciphertext ; S63, the data owner sets the access policy W and encrypts the AES symmetric key based on the access structure , get the key ciphertext .

5. The method according to claim 1, characterized in that After step S40, the method further includes: S80, when the data owner publishes a data transaction, enter the user's public key , the timestamp of the current transaction The hash address of the target data transaction in the Interstellar File System , create a data transaction , and after verifying the data transaction The legality of data trading Write to the blockchain.

6. The method according to claim 5, characterized in that The data transaction includes a data storage transaction and a data access transaction, and the verification of the data transaction includes a data storage transaction verification and a data access transaction verification; The data storage transaction verification S81 specifically includes: S811, the data owner distributes each key fragment , a storage transaction will be created and published to the blockchain ,in, is the current transaction timestamp, Key fragment The storage address in IPFS; S812, data owner uses private key For transactions Sign , and then generate the corresponding anonymous certificate ; S813, allowing any user on the blockchain to use a public key and anonymous certificates For transactions Verify; if the verification is successful, the transaction is allowed to be written into the blockchain; otherwise, the transaction is ignored; The data access transaction verification S82 specifically includes: S821, Data users are randomly selected , calculate the corresponding access public key , safely save access private keys ; S822, data owner randomly selected , is the ciphertext data Calculate the corresponding commitment value , and set the ElGamal commitment value set ; S823, data owner creates data access transaction ,use right sign , generate the corresponding anonymous certificate , and then Publish to the blockchain.

7. The method according to claim 1, characterized in that After S40, the following steps are also included: S90: During the data user’s data access process, the blockchain conducts commitment verification on the access request in the transaction at preset intervals to ensure the legitimacy of the access request.

8. The method according to claim 7, characterized in that The S90 specifically includes: S91, the data user sends a ciphertext to the blockchain at intervals of the preset period. Access Request ; In the formula, Indicates information label, Represents an anonymous certificate. Indicates the commitment value; S92, blockchain parses the commitment value in the access request Elements in and , calculated , and Sent to the data owner; In the formula, To access the public key; S93, the data owner receives Then verify whether the following formula is true: ； If established, notify the blockchain to send the ciphertext Storing hash values ​​in the InterPlanetary File System Return to the data user; otherwise, access is denied and the protocol ends; In the formula, For private key .

9. An access control system, characterized in that: include: A memory, a processor, and an access control program stored in the memory and executable on the processor, wherein the access control program implements the steps of the access control method according to any one of claims 1 to 8 when executed by the processor.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores an access control program, and when the access control program is executed by a processor, the steps of the access control method according to any one of claims 1 to 8 are implemented.

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